When does a DUI become a felony in Florida?

The common statement that "a third DUI is a felony" is only partly right, and the part that's wrong matters.

A third conviction within ten years of a prior is a third-degree felony — thirty days mandatory to five years, a ninety-day vehicle impoundment, and a ten-year revocation.

A third outside that ten-year window is a misdemeanor, though with elevated fines and up to twelve months.

A fourth or subsequent conviction is a felony regardless of timing. Florida counts priors across a lifetime for this purpose, so a conviction from decades ago still counts toward the fourth.

Separately, any DUI causing serious bodily injury is a third-degree felony, and any DUI causing death is a second-degree felony — now a first-degree felony where the person has a prior qualifying fatality conviction.

So the answer turns on two different clocks and one severity question.